Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

T1 - Phase 1 - Integrated (I) > MSK - Biochemistry - Actin & Intermediate Filaments; Collagen; ECM > Flashcards

MSK - Biochemistry - Actin & Intermediate Filaments; Collagen; ECM Flashcards

1
Q

What is the inheritance pattern of Duchenne’s muscular dystrophy?

What is the life expectancy of affected individuals?

A

X-linked recessive;

< 35

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Duchenne’s muscular dystrophy affects which muscles first?

What muscles often appear hypertrophied?

What is the usual cause of death?

A

The pelvic girdle;

calf muscles;

loss of function of diaphragmatic and cardiac muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What type of muscle is the principal type affected in Duchenne’s muscular dystrophy?

What is a common first sign?

A

Voluntary;

failure of child to walk normally or hold normal posture - may walk on toes due to muscle contractures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Dystrophin binds actin to ____________, which binds to extracellular laminin.

A

α,β-dystroglycan

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What disease is similar to Duchenne’s muscular dystrophy but is less severe and results later in life?

A

Becker muscular dystrophy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What two substances (one mineral and one nucleotide) are vital to F-actin polymerization from G-actin?

A

ATP, Mg2+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

The ATP-binding cleft is on which end of the G-actin monomer?

A

The - end

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

G-actin must be bound to ___ to polymerize into F-actin.

α- and β-tubulin must be bound to ___ to polymerize into microtubule protofilaments.

A

ATP;

GTP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

True/False.

Both the GTP associated with microtubules and the ATP associated with actin will hydrolyze relatively soon after polymerization?

A

True

(although the ATP-actin hydrolyzes much sooner)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the three cellular proteins regulating actin polymerization?

A

Cofilin,

profilin,

thymosin-β4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What protein breaks off pieces of F-actin?

A

Cofilin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What protein exchanges ADP for ATP on G-actin, allowing it to be used in polymerization?

(It just adds a phosphate group to the ADP)

A

Profilin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What protein sequesters ATP G-actin to prevent polymerization?

A

Thymosin-β4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What protein binds the + end of F-actin to prevent polymerization?

What protein binds the - end of F-actin to stabilize actin?

A

CapZ;

tropomodulin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What protein binds the + end of F-actin to prevent polymerization?

A

CapZ

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What protein binds the - end of F-actin to stabilize actin?

A

Tropomodulin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What protein helps promote the unbranched form of F-actin?

What protein helps promote the branched form of F-actin?

A

Formin;

Arp2/3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What type of filament is especially important in cell migration (e.g. chemotaxis)?

A

Actin (microfilaments)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the four steps of cell movement during chemotaxis?

A

1. Foot process (lamellipodium) formation

2. Adhesion at the front of the cell

3. Translocation as the cell shifts forwards

4. Deadhesion at the back of the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What type of protein cross-links the cytoskeleton to the ECM?

A

Integrins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What type of protein cross-links actin into a meshwork on the P-face?

A

Spectrin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Hereditary spherocytosis can be caused by defects in what three proteins?

A

Spectrin, protein 4.1, ankyrin.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What type(s) of intermediate filament are especially prevalent in epithelial tissues?

A

Cytokeratins (acidic and basic)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What type(s) of intermediate filament are especially prevalent in muscle?

A

Desmin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What type(s) of intermediate filament are especially prevalent in mesenchymal tissues?

A

Vimentin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What type(s) of intermediate filament are especially prevalent in glial cells?

A

GFAP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What type(s) of intermediate filament are especially prevalent in neural tissues?

A

Neurofilaments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What type(s) of intermediate filament is especially prevalent in the nucleus?

A

Lamins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What protein other than spectrin or dytrophin is especially important in cross-linking actin into its structure on the inner cell membrane?

A

Fimbrin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What protein is especially important in organizing actin stress fibers during cell migration?

A

α-actinin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Spectrin and dystrophin are both in what supergene family?

A

Spectrin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What are some of the physical features commonly seen in type I osteogenesis imperfecta?

What are some other common occurrences?

A

Blue sclera, triangular shape;

frequent fractures, hearing loss (beginning in the twenties), scoliosis, thin skin, loose joints, low muscle tone, brittle teeth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What inheritance does type I osteogenesis imperfecta exhibit?

It is due to a defect in what?

A

Autosomal dominant;

type I collagen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What type of osteogenesis imperfecta frequently results in death during embryogenesis or birth?

A

Type II

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What gene is associated with osteogenesis imperfecta type I?

A

COL1A1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

How is osteogenesis imperfecta treated?

What is the mechanism of action?

A

Bisphosphonates;

osteoclast inhibition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

_______________ are useful for treating osteoporosis and osteogenesis imperfecta by inhibiting osteoclasts because they mimic ______________, which is needed for normal osteoclastic activity.

A

Bisphosphonates;

pyrophosphates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

How do individuals with type II osteogenesis imperfecta typically die?

A

Severe bone fracturing during the birthing process

39
Q

What effect do bisphosphonates tend to have on apoptosis in bone cells?

A

Increased osteoclast apoptosis;

decreased osteoblast apoptosis

40
Q

The basic structure of collagen that gives it its strength is a:

A

triple helix

41
Q

What is the basic repeating amino acid code for collagen?

What amino acids make up the variable portions?

A

Gly - X - Y;

X,Y = proline or hydroxyproline

42
Q

Is the collagen helix a right- or left-handed helix?

A

Left

43
Q

What type of bonding is extremely prevalent in collagen, binding the strands together?

A

Hydrogen bonding

44
Q

Describe collagen in terms of tensile strength and elasticity.

Describe elastin in terms of tensile strength and elasticity.

A

High tensile strength, low elasticity;

low tensile strength, high elasticity;

45
Q

Vitamin C is needed for what step of collagen formation?

Why is this step important?

A

Proline hydroxylation;

it stabilizes the triple helix

46
Q

True/False.

Without Vitamin C, collagen cannot be synthesized.

A

False.

Vitamin C is responsible for post-translational proline hydroxylation.

(without vitamin C, the collagen strands are simply less stable and more easily degraded)

47
Q

Vitamin C is a cofactor of what enzyme involved in post-translational collagen modification?

A

4-prolyl-hydroxylase

48
Q

Which five collagen fibrils follow the characteristic triple helix structure?

A

I, II, III, V, XI

49
Q

What type of collagen is a higher order structure found in the basement membrane?

A

Type IV

50
Q

What type of collagen is an anchoring type that connects the dermal and epidermal layers?

A

Type VII

51
Q

What organ systems are most susceptible in Alport’s syndrome?

What is the main genetic defect in Alport’s syndrome?

A

Kidney, ears (ossicles), and eyes (cornea);

type IV collagen defects

52
Q

What is the most common form of inheritance seen in Alport;s syndrome?

A

X-linked

53
Q

Where is type I collagen found?

A

Most connective tissue

54
Q

Where is type II collagen found?

A

Cartilage and vitreous humor

55
Q

Where is type III collagen found?

A

Extensible connective tissue

56
Q

Where is type IV collagen found?

What structure does it have?

A

Basal lamina;

sheet-like networks

57
Q

Where are type V and XII collagen found?

A

Tissues containing type I collagen

58
Q

Where is type VII collagen found?

A

Anchoring basal lamina to underlying connective tissue

59
Q

What protein serves as a scaffold for tropoelastin?

Mutations in this protein lead to what disorder?

A

Fibrillin;

Marfan’s syndrome

60
Q

What is a (typically present) symptom of homocystinuria that differentiates it from Marfan’s syndrome?

A

Intellectual disability

61
Q

What are the first three steps of collagen synthesis?

(starting with a transcribed collagen mRNA)

A

1. mRNA is translated into pre-procollagen

2. Hydroxylation of select proline residues

3. Glycosylation of select lysine residues

62
Q

What are the second three steps of collagen synthesis?

(starting here with hydroxylated and glycosylated procollagen chains)

A
  1. Three pro-alpha-chains come together into an alpha-helix
  2. Procollagen secreted from cell
  3. Procollagen ends cleaved off by procollagen peptidase

(This is now tropocollagen)

63
Q

Following secretion of procollagen from the cell and cleavage of its ends to form tropocollagen, what happens?

A

Lysyl oxidase cross-links mature collagen fibrils

64
Q

A deficiency of lysyl oxidase leads to what disorder?

Lysyl oxidase is used to cross-link what together?

What element is necessary for its function?

A

Menke’s syndrome;

collagen fibrils;

copper

65
Q

Ehrlos-Danlos syndrome is caused by a mutation in the ADAMTS2 gene. This leads to a deficiency in what enzyme?

What does this enzyme do?

A

Procollagen peptidase;

cleaves procollagen ends to form tropocollagen

66
Q

What are three of the few enzymes in the body that require copper (Cu2+) as a cofactor?

A

Tyrosinase,

dopamine β-hydroxylase,

lysyl oxidase

67
Q

How does the ECM serve as a source of growth and chemotactic factors?

A

Growth factors are bound to (sequestered in) proteoglycans until metalloproteases release them

68
Q

What is the basic makeup of ECM?

(3 main players)

A

Hydrated gel

+

reinforcing fibers throughout

+

multiadhesive signaling proteins

69
Q

What proteoglycan is associated with the basement membrane?

What collagen type is associated with the basement membrane?

What multiadhesive proteins are associated with the basement membrane?

A

Perlecan;

type IV;

fibronectin, laminin

70
Q

What proteoglycan is associated with the basement membrane?

A

Perlecan

71
Q

What collagen type is associated with the basement membrane?

A

Type IV

72
Q

What multiadhesive proteins are associated with the basement membrane?

A

Fibronectin, laminin

73
Q

What are the two main functions of multiadhesive proteins in the ECM?

A

Signaling,

binding cells in place within the ECM

74
Q

What is a glycosaminoglycan (GAG) in terms of structure?

Are they osmotically active?

A

An unbranched polysaccharide made of repeating disaccharide units (often a uronic acid + an amino sugar);

yes, they keep tissues hydrated by storing water

75
Q

Are glycosaminoglycans eosinophilic or basophilic?

Why?

A

Basophilic;

lots of SO4- and COO- groups

76
Q

What is a proteoglycan (found in the ECM)?

A

A core protein with tons of attached glycosaminoglycans

(basically a protein with tons of sugars sticking off of it)

(one branch of the ‘Christmas tree’ seen in the attached illustration)

77
Q

What is the major core protein of proteoglycans found on articular cartilage?

True/false.

It can absorb and release synovial fluid as needed (according to pressures).

A

Aggrecan;

true

78
Q

What are the two main cartilaginous proteins that are often degraded in osteoarthritis?

A

Type II collagen;

aggrecan

79
Q

Is hyaluronic acid a proteoglycan?

A

No;

it is a glycosaminoglycan forming the ‘trunk’ to which proteoglycan ‘branches’ attach

80
Q

What type of proteoglycan is primarily found in cartilage?

What type of proteoglycan is primarily found in basal lamina?

What type of proteoglycan binds type I collagen and is widespread in ECM?

A

Aggrecan;

perlecan;

decorin

81
Q

What two proteoglycans and one protein sequester TGF-β?

A

Aggrecan, decorin

(storing it until the tissue is damaged and growth is needed);

fibrillin

(that’s why Marfan’s syndrome patients have such long bones)

82
Q

Why do individuals with Marfan’s syndrome grow such long bones?

A

Fibrillin (which is missing or defective in these patients) sequesters TGF-β

83
Q

What is a super-abundant protein of the ECM that binds type I collagen, fibrin, and proteoglycans to integrins on cell membranes, essentially binding cells to ECM?

A

Fibronectin

84
Q

What is fibronectin’s main function?

A

Connecting cells to ECM

85
Q

Multiadhesive proteins are ECM proteins such as fibronectin and laminin. What is another protein in this family that is essential to proper blood coagulation?

A

von Willebrand’s factor

86
Q

What is the principal multiadhesive protein of the basal lamina?

What cell membrane protein does it bind?

What particular basal lamina protein does it bind?

A

Laminin-1;

α,β-dystroglycan;

type IV collagen

87
Q

What are the two main families of protein involved in cell-to-cell adhesion?

A

Cadherins (found in desmosomes);

CAMs (cell adhesion molecules)

88
Q

Inflammatory molecules induce endothelial cells to express what protein that loosely interacts with leukocytes?

After that initial velcro-like contact, what stronger protein binds the leukocyte and helps is extravasate?

A

P-selectins;

integrins

89
Q

Describe integrin structure.

True/False.

Integrins are present in both active and inactive forms.

A

Heterodimeric (α and β)

True.

90
Q

The inactive conformation of an integrin protein is:

The active conformation of an integrin protein is:

A

Bent;

extended

91
Q

What are a few intracellular pathways that may be involved in different integrin protein signaling?

A

ERK 1/2

The Phosphatidyl Inositol 3- Kinase (PI3K) pathway

Rac / Rho / Cdc42 G-proteins

92
Q

The _ _ _ sequence is important to integrin signaling.

A

RGD

93
Q

What multiadhesive protein is often found in the basal lamina along with perlecan?

A

Agrin

94
Q

Are collagen chains stabilized by interchain or intrachain hydrogen bonds?

A

Interchain

(there are no intrachain H-bonds)

T1 - Phase 1 - Integrated (I) (28 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions